1. Field of the Disclosure
The present disclosure relates to products made or derived from tobacco or other smokable material that are intended for human consumption. In particular, the disclosure relates to filter material for filter elements of smoking articles, such as cigarettes, and related methods for producing such filter material and associated filter elements.
2. Description of Related Art
Popular smoking articles, such as cigarettes, can have a substantially cylindrical rod-shaped structure and can include a charge, roll or column of smokable material, such as shredded tobacco (e.g., in cut filler form), surrounded by a paper wrapper, thereby forming a so-called “smokable rod” or “tobacco rod.” Normally, a cigarette has a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Typically, a filter element comprises plasticized cellulose acetate tow circumscribed by a paper material known as “plug wrap,” and the filter element is attached to one end of the tobacco rod using a circumscribing wrapping material known as “tipping material.” It also can be desirable to perforate the tipping material and plug wrap, in order to provide dilution of drawn mainstream smoke with ambient air. Descriptions of cigarettes and the various components thereof are set forth in Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) (1999). A cigarette is employed by a smoker by lighting one end thereof and burning the tobacco rod. The smoker then receives mainstream smoke into his/her mouth by drawing on the opposite end (e.g., the filter end) of the cigarette.
The currently available filter technology for forming filter elements may have several drawbacks. For example, conventional filter elements comprising a cellulose acetate tow, although being characterized as biodegradable, may require an undesirably long time to actually biodegrade. In some instances, the biodegradation period may be on the order of two to ten years. In response, alternate filter materials have been proposed, such as gathered paper, nonwoven polypropylene web or gathered strands of shredded web. However, even if filter elements comprising such alternate materials exhibit accelerated biodegradability over conventional cellulose acetate tow filter elements, the effect thereof on the mainstream smoke may not meet the expectations of the smoker. That is, conventional cellulose acetate tow is generally plasticized with an appropriate plasticizer, such as triacetin, upon the tow being bloomed and formed into the filter rod from which the filter elements are obtained. In this regard, the triacetin plasticizer provides a particular effect on the mainstream smoke (i.e., taste) that is pleasant to the smoker or has otherwise become expected by the smoker. One issue with alternate filter materials is that those materials may not necessarily blend with or suitably receive a plasticizer such as triacetin. That is, even if such alternate filter materials receive the triacetin, the effect of the combination on the mainstream smoke, for example, the taste of the smoke, may not be pleasant to the smoker or otherwise be similar enough to the sensation expected by the smoker who is accustomed to the organoleptic properties associated with triacetin-treated cellulose acetate tow filter elements.
Certain filter elements for cigarettes have been developed which contain materials that may promote biodegradation of filter elements following use. For example, certain additives have been noted (e.g., water soluble cellulose materials, water soluble fiber bonding agents, starch particles, photoactive pigments, and/or phosphoric acid) which can be added to filter materials to enhance degradability. See, for example, U.S. Pat. No. 5,913,311 to Ito et al.; U.S. Pat. No. 5,947,126 to Wilson et al.; U.S. Pat. No. 5,970,988 to Buchanan et al.; and U.S. Pat. No. 6,571,802 to Yamashita; and US Pat. Appl. Publ. Nos. 2009/0151735 to Robertson and 2011/0036366 to Sebastian. In some cases, conventional cellulose acetate filter material has been replaced with other materials, such as moisture disintegrative sheet materials, extruded starch materials, or polyvinyl alcohol. See U.S. Pat. No. 5,709,227 to Arzonico et al; U.S. Pat. No. 5,911,224 to Berger; U.S. Pat. No. 6,062,228 to Loercks et al.; and U.S. Pat. No. 6,595,217 to Case et al. It has also been suggested that the incorporation of slits into a filter element may enhance biodegradability, as described in U.S. Pat. No. 5,947,126 to Wilson et al. and U.S. Pat. No. 7,435,208 to Garthaffner. Biodegradability has also been proposed to be imparted by use of certain adhesives, such as described in U.S. Pat. No. 5,453,144 to Kauffman et al. and US Pat. Appl. Publ. 2012/0000477 to Sebastian et al. Another possible means for enhancing biodegradability is replacing the conventional cellulose acetate filter material with a core of a fibrous or particulate cellulose material coated with a cellulose ester, as described in U.S. Pat. No. 6,344,349 to Asai et al.
Further advancements in filter elements and apparatuses and methods for producing the same may be desirable, wherein such advancements maximize or otherwise enhance the biodegradability of the filter tow/filter element, while blending with conventional plasticizers to retain the sensory effects on the mainstream smoke (i.e., smoke taste), expected by the smoker.